1. Technical Field
The present invention relates to a piezoelectric driving device, a piezoelectric drive controlling method, and an electronic device. More particularly, the present invention relates to a piezoelectric driving device, a piezoelectric drive controlling method, and an electronic device which can reduce the hysteresis of a laminated piezoelectric body obtained by laminating a plurality of piezoelectric bodies.
2. Related Art
There has conventionally been known a bimorph actuator made by superimposing two piezoelectric plates on each other. For example, Japanese Patent Application Publication No. 2001-156352 discloses a bimorph actuator that is made by superimposing first and second piezoelectric plates on each other and then joining them together. In the bimorph actuator, a voltage is applied between the first and second piezoelectric plates and thus the actuator is expanded and contracted in different directions along longitudinal directions of both piezoelectric plates. At this time, one piezoelectric plate is used as a means for driving the actuator and the other piezoelectric plate is used as a sensor for correcting hysteresis. The output of the sensor is used for the feedback control of the voltage that is applied to the piezoelectric plate for driving the actuator.
A piezoelectric actuator has hysteresis between an applied voltage and a displacement amount in accordance with increase and decrease directions of the applied voltage. There is a problem that the hysteresis degrades the linearity characteristic of the piezoelectric actuator and thus the displacement amount cannot be controlled with high precision using the piezoelectric actuator.
Since the bimorph actuator according to Japanese Patent Application Publication No. 2001-156352 does not apply a voltage to the piezoelectric plate used as a sensor, the displacement amount cannot be controlled if a feedback control is not performed. In addition, since the displacement amount of the actuator is controlled with one piezoelectric plate, it is difficult to improve linearity. Therefore, there is a need to provide a piezoelectric driving device and a piezoelectric drive controlling method for controlling the displacement amount of a piezoelectric actuator with good linearity, and an electronic device using the device and method.